tells Mina that he has fallen in love with her. Mamie Gummer as Dr. Mina Minard: Mina is a doctor who "only works solo" and loses confidence easily due to a misdiagnosis earlier in her career that led to the death of a patient, a little boy named Eric. She is highly competitive at work. She owns a chicken named Dinner that was given to her by a grateful patient. In episode 4 Mina says that her father is the head of a major Boston hospital, and when she misdiagnosed Eric he wiped her resume clean of the incident. She appears to have some kind of attraction to Cole after they share some close moments. In episode 8, Mina sleeps with Tommy while she is drunk after a party for her new god-daughter. In episode 12 Hold on tight Mina becomes Ryan's doctor without Keeton knowing. At the end of the episode Keeton fires Mina for lying to him and will never let her be Ryan's doctor. Rachelle Lefevre as Dr. Ryan Clark: Ryan's parents were missionaries, and she grew up all over the world. She was bitten by an assassin bug when she was eight years old which went untreated causing her to develop Chagas disease. Twenty years later, the disease has caused irreversible heart damage and leads her to going into heart failure. She is in an on and off again relationship with Ben Keeton, although he eventually fully commits to her once he realizes it is time for him to move on from his past. When he discovers the truth about Ryan's condition, he is worried sick, which leads to both of them declaring their love for each other. When Ryan has to go to New York for her heart to get her on a transplant list, she is joined by Ben at the airport, who decides to come with her. Jonathan Castellanos as Charlie: When Charlie was 9, his parents abandoned him. He now works at the clinic, and "supposedly" lives in a hostel. It is shown that he actually house-sits condos for 6 months a year, and has a bed under a lab in the clinic as well. He is good friends with both Tommy and Cole. Charlie has a crush on Brenner and was worried that she did not know his name. Charlie has given voice to the titles of episode 3 and 4.